An On-Machine Error Measurement System for Micro-Machining

Author(s):  
Shih-Ming Wang ◽  
Han-Jen Yu ◽  
Yi-Hung Liu ◽  
Da-Fun Chen

Technology development trends towards the ability to manufacture ever smaller parts and feature sizes with increased precision and decreased cost. Micro machining is one of the important manufacturing methods to fulfill the requirements from the industry. The objective of this paper is to develop an on-machine error measurement system that can identify the micro machining errors for error compensation so that the machining accuracy of a meso-scale machine tool (mMT) can be enhanced. Because of the difficulty in handling and repositioning the miniature workpiece, the error measurement system should be non-contact and on-machine executable. To meet this requirement, a vision-based error measurement system integrating image re-constructive technology, camera pixel correction, and model comparison algorithm error was developed in this study. The proposed measurement system consists of a CCD with CCTV lens, a precision 3-DOF platform, image re-construction sub-system, and contour error calculation sub-system. By adopting Canny Edge Detection algorithm and camera pixel calibration method, the contour of a machined workpiece can be identified and compared to the pixel-based theoretical contour model of the workpiece to determine the micro machining errors. Because the system does not have to remove the machined workpiece from the CNC machine tool, errors due to re-installing and re-positioning can be avoided. To prove the feasibility of the developed algorithm and system, measurement results obtained from the vision-based measurement system were compared with the measurements of CMM, and error compensation experiment conducted on a 3-DOF mMT was also conducted. The results have shown the good feasibility and effectiveness of the developed system.

2013 ◽  
Vol 284-287 ◽  
pp. 1723-1728
Author(s):  
Shih Ming Wang ◽  
Han Jen Yu ◽  
Hung Wei Liao

Error compensation is an effective and inexpensive way that can further enhance the machining accuracy of a multi-axis machine tool. The volumetric error measurement method is an essential of the error compensation method. The measurement of volumetric errors of a 5-axis machine tool is very difficult to be conducted due to its complexity. In this study, a volumetric-error measurement method using telescoping ball-bar was developed for the three major types of 5-axis machines. With the use of the three derived error models and the two-step measurement procedures, the method can quickly determine the volumetric errors of the three types of 5-axis machine tools. Comparing to the measurement methods currently used in industry, the proposed method provides the advantages of low cost, easy setup, and high efficiency.


2010 ◽  
Vol 154-155 ◽  
pp. 390-395 ◽  
Author(s):  
Hao Huang ◽  
Xiang Yang Lei ◽  
Jian Wang ◽  
Qiao Xu ◽  
Liang Yu He ◽  
...  

The causes of machining errors are very complicated and apt to mutual influence in aspheric grinding, so it is difficult to improve machining accuracy by control one cause. To compensate the machining error of large aspheric grinding, an error-compensation technique using on-machine profile measurement system in three axes grinding machine are presented. To verify the effectiveness of the compensation machining and the reliability of the measurement system, experiments on high-precision grinding machine were performed. Moreover, the compensation machining with the on-machine measurement substantially decreases the machining errors and improve machining accuracy by more than 45%, compared with the non-compensation machining.


Author(s):  
Hongwei Liu ◽  
Rui Yang ◽  
Pingjiang Wang ◽  
Jihong Chen ◽  
Hua Xiang

The objective of this research is to develop a novel correction mechanism to reduce the fluctuation range of tools in numerical control (NC) machining. Error compensation is an effective method to improve the machining accuracy of a machine tool. If the difference between two adjacent compensation data is too large, the fluctuation range of the tool will increase, which will seriously affect the surface quality of the machined parts in mechanical machining. The methodology used in compensation data processing is a simplex method of linear programming. This method reduces the fluctuation range of the tool and optimizes the tool path. The important aspect of software error compensation is to modify the initial compensation data by using an iterative method, and then the corrected tool path data are converted into actual compensated NC codes by using a postprocessor, which is implemented on the compensation module to ensure a smooth running path of the tool. The generated, calibrated, and amended NC codes were immediately fed to the machine tool controller. This technique was verified by using repeated measurements. The results of the experiments demonstrate efficient compensation and significant improvement in the machining accuracy of the NC machine tool.


Author(s):  
Xicong Zou ◽  
Xuesen Zhao ◽  
Guo Li ◽  
Zengqiang Li ◽  
Zhenjiang Hu ◽  
...  

On-machine error compensation (OMEC) is efficient at improving machining accuracy without increasing extra manufacturing cost, and involves the on-machine measurement (OMM) of machining accuracy and modification of program code based on the measurement results. As an excellent OMM technique, chromatic confocal sensing allows for the rapid development of accurate and reliable error compensation technique. The present study integrated a non-contact chromatic confocal probe into an ultra-precision machine for OMM and OMEC of machined components. First, the configuration and effectiveness of the OMM system were briefly described, and the relevant OMEC method was presented. With the OMM result, error compensation software was then developed to automatically generate a modified program code for error compensation. Finally, a series of cutting experiments were performed to verify the validity of the proposed OMEC method. The experimental results demonstrate that the proposed error compensation method is reliable and considerably improves the form error of machined components.


2005 ◽  
Vol 291-292 ◽  
pp. 513-518 ◽  
Author(s):  
Ming Jun Chen ◽  
Ying Chun Liang ◽  
Ya Zhou Sun ◽  
W.X. Guo ◽  
Wen Jun Zong

In order to machine complex free surface parts, a micro NC (numerical control) three-dimensional machine tool is developed, integrated the PMAC control. Based on this NC machine tool, the influencing of the technological and tool’s parameters on machining accuracy of micro complex surface parts are analyzed, and the cause to lead to the machining errors is explained. Therefore, the cutting parameters and tool geometry parameters to machine micro complex surface, such as the human’s face, can be selected optimally. Finally, the micro complex human’s face is machined on this developed micro machine tool under optimal parameters. The experimental results show that the machined surface is smooth and continuous. The machined quality is satisfied.


2010 ◽  
Vol 447-448 ◽  
pp. 529-533 ◽  
Author(s):  
Shih Ming Wang ◽  
Han Jen Yu ◽  
Jih Pong Yang ◽  
Da Fan Chen

To further enhance the accuracy of a micro milling process, an effective error measurement method and error compensation method are necessary. An on-machine vision-based error measurement method integrating image re-constructive technology, camera pixel correction, and model comparison algorithm to provide the capability of non-contact measurement for micro-machined workpiece error was developed. With use of Canny Edge Detection algorithm and camera pixel calibration, the edge of the contour of a machined workpiece can be identified and used to re-construct the actual shape of the workpiece. The actual shape will then be compared to the theoretical shape of the workpiece. To prove the feasibility of the proposed methods and system, experiments were conducted. The results have shown the success of enhacing machining accuracy for a micro milling process.


2013 ◽  
Vol 819 ◽  
pp. 33-37 ◽  
Author(s):  
Jin Tao Lai ◽  
Xin Hua Yao ◽  
Wen Li Yu ◽  
Jian Zhong Fu

The error distribution of a machined NURBS surface is complex to describe since the machined surface isnt that easy to obtain. A new method for machined NURBS surface description based on inspection database of on-machine probing is presented. The main idea is to approximate the machined surface using the inspection data and the basis functions of the nominal NURBS surface and to get the error distribution of the surface. A virtual part with a NURBS surface is presented and its error caused by the interaction of the machine-tool-workpiece is obtained using the FEA method at the inspection points. A machined NURBS surface is achieved and the error distribution of the surface is expressed. This method provides a new way in error compensation and it will improve the machining accuracy of a NURBS surface.


2008 ◽  
Vol 381-382 ◽  
pp. 187-190 ◽  
Author(s):  
Ryo Kobayashi ◽  
Shinya MORITA ◽  
Y. Watanabe ◽  
Y. Uehara ◽  
W. Lin ◽  
...  

A non-contact on-machine measurement system has been developed since various precise machines are getting lighter and smaller; therefore, processing with nano-precision is demanded recently. This system makes possible to measure with high precision without any damages and it is unnecessary for workpieces to attach or detach from a machine tool. Moreover, this system achieves on-machine form error compensation with high precision. On the other hand, the details of the system performances are still unknown. This study focuses on evaluating the performances by the comparison of the results that measured by this system and an existing measurement instrument under various conditions. As a result, this system shows an equivalent capability of measurement with high precision as the existing measurement instrument.


2020 ◽  
Vol 56 ◽  
pp. 1286-1293 ◽  
Author(s):  
Shinya Kidani ◽  
Naruhiro Irino ◽  
Shigeaki Maruyama ◽  
Kayoko Taniguchi ◽  
Toru Fujimori ◽  
...  

2014 ◽  
Vol 513-517 ◽  
pp. 4202-4205
Author(s):  
Hong Xin Zhang ◽  
Qian Jian Guo

With the increasing requirements of the machining accuracy of CNC machine tools, the impact of thermal deformation is growing. Thermal error compensation technology can predict and compensate the thermal errors in real-time, and improve the machining accuracy of the machine tool. In this paper, the research objects of thermal error compensation is expanded to the volumetric error of the machine tool, the volumetric error modeling of a three-axis machine tool is fulfilled and a compensator is developed for the compensation experiment, which provides scientific basis for the improvement of the machining accuracy.


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